2006 GX470 rear strut replacement

[bvk_houtx]

I changed the struts on my 2006 GX470.  I have 158,000+ miles on the car.  I checked with the dealer and local garages and was quoted prices ranging from $1500 - $2500. My wife is concerned because after I changed the struts (LuftMeister brand) she does not hear the air leaving the air bags when we park the car.  To be honest, I never heard what she says she used to hear but then again my hearing 'ain't what it used to be.....:)'.  The old struts needed to be replaced and I can definitely tell the difference in the ride.  I'm just not sure how the airbag system is supposed to work.  Do the bags stay inflated or do the slowly deflate and re-inflate when you start the car?  Thanks in advance for any and all feed-back.